Qemu: i386: leakage of stack memory to guest in kvmvapic.c
Published May 25, 2016
6.5
MEDIUMCVSS 3.1
EPSS 0.37%
Description
The patch_instruction function in hw/i386/kvmvapic.c in QEMU does not initialize the imm32 variable, which allows local guest OS administrators to obtain sensitive information from host stack memory by accessing the Task Priority Register (TPR).
Affected products
No data.
Configuration 2
- 12.04
- 14.04
- 15.10
- 16.04
Configuration 3
- 8.0
Configuration 4
- 6.0
- 7.0
- 8
- 9
- 10
- 11
- 7.0
- 7.4
- 7.5
- 7.6
- 7.7
- 7.0
- 7.4
- 7.6
- 7.7
- 7.6
- 7.7
- 7.0
Configuration 5
- 4.0
Running on/with
- 7.0
No data.
Red Hat Enterprise Linux 7
qemu-kvm-10:1.5.3-141.el7
Fixed · RHSA-2017:1856
Red Hat Enterprise Linux OpenStack Platform 6.0 (Juno) for RHEL 7
qemu-kvm-rhev-10:2.9.0-10.el7
Fixed · RHSA-2017:2408
Red Hat Enterprise Linux OpenStack Platform 7.0 (Kilo) for RHEL 7
qemu-kvm-rhev-10:2.9.0-10.el7
Fixed · RHSA-2017:2408
Red Hat OpenStack Platform 10.0 (Newton)
qemu-kvm-rhev-10:2.9.0-10.el7
Fixed · RHSA-2017:2408
Red Hat OpenStack Platform 11.0 (Ocata)
qemu-kvm-rhev-10:2.9.0-10.el7
Fixed · RHSA-2017:2408
Red Hat OpenStack Platform 8.0 (Liberty)
qemu-kvm-rhev-10:2.9.0-10.el7
Fixed · RHSA-2017:2408
Red Hat OpenStack Platform 9.0 (Mitaka)
qemu-kvm-rhev-10:2.9.0-10.el7
Fixed · RHSA-2017:2408
Red Hat Virtualization 4 for Red Hat Enterprise Linux 7
qemu-kvm-rhev-10:2.9.0-14.el7
Fixed · RHSA-2017:2392
Red Hat Enterprise Linux 5
kvm
Not affected
Red Hat Enterprise Linux 5
xen
Not affected
Red Hat Enterprise Linux 6
qemu-kvm
Not affected
Red Hat Enterprise Linux OpenStack Platform 5 (Icehouse)
qemu-kvm-rhev
Will not fix
Red Hat OpenStack Platform 12 (Pike)
qemu-kvm-rhev
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 7 | qemu-kvm-10:1.5.3-141.el7 | Fixed | RHSA-2017:1856 |
| Red Hat Enterprise Linux OpenStack Platform 6.0 (Juno) for RHEL 7 | qemu-kvm-rhev-10:2.9.0-10.el7 | Fixed | RHSA-2017:2408 |
| Red Hat Enterprise Linux OpenStack Platform 7.0 (Kilo) for RHEL 7 | qemu-kvm-rhev-10:2.9.0-10.el7 | Fixed | RHSA-2017:2408 |
| Red Hat OpenStack Platform 10.0 (Newton) | qemu-kvm-rhev-10:2.9.0-10.el7 | Fixed | RHSA-2017:2408 |
| Red Hat OpenStack Platform 11.0 (Ocata) | qemu-kvm-rhev-10:2.9.0-10.el7 | Fixed | RHSA-2017:2408 |
| Red Hat OpenStack Platform 8.0 (Liberty) | qemu-kvm-rhev-10:2.9.0-10.el7 | Fixed | RHSA-2017:2408 |
| Red Hat OpenStack Platform 9.0 (Mitaka) | qemu-kvm-rhev-10:2.9.0-10.el7 | Fixed | RHSA-2017:2408 |
| Red Hat Virtualization 4 for Red Hat Enterprise Linux 7 | qemu-kvm-rhev-10:2.9.0-14.el7 | Fixed | RHSA-2017:2392 |
| Red Hat Enterprise Linux 5 | kvm | Not affected | n/a |
| Red Hat Enterprise Linux 5 | xen | Not affected | n/a |
| Red Hat Enterprise Linux 6 | qemu-kvm | Not affected | n/a |
| Red Hat Enterprise Linux OpenStack Platform 5 (Icehouse) | qemu-kvm-rhev | Will not fix | n/a |
| Red Hat OpenStack Platform 12 (Pike) | qemu-kvm-rhev | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
CVSS:3.0/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N
AV:L/AC:L/Au:N/C:P/I:N/A:N
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (10 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 0.37% (0.00372) | 28.77th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.38% (0.00375) | 29.11th | v5 (v2026.06.15) |
| Mar 17, 2025 | 0.08% (0.00085) | 22.32th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.06% (0.00059) | 27.15th | v3 (v2023.03.01) |
| Jun 6, 2024 | 0.06% (0.00059) | 25.07th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.06% (0.00059) | 23.06th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.28% (0.01282) | 68.34th | v2 (v2022.01.01) |
| Feb 22, 2023 | 1.28% (0.01282) | 68.05th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.28% (0.01282) | 65.91th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.28% (0.01282) | 41.72th | v2 (v2022.01.01) |
References (14)
- http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=691a02e2ce0c413236a78dee6f2651c937b09fb0 x_refsource_CONFIRM
- http://www.securityfocus.com/bid/86067 vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
- http://www.ubuntu.com/usn/USN-2974-1 vendor-advisoryx_refsource_UBUNTUThird Party Advisory
- https://access.redhat.com/errata/RHSA-2017:1856 vendor-advisoryx_refsource_REDHATThird Party Advisory
- https://access.redhat.com/errata/RHSA-2017:2392 vendor-advisoryx_refsource_REDHATThird Party Advisory
- https://access.redhat.com/errata/RHSA-2017:2408 vendor-advisoryx_refsource_REDHATThird Party Advisory
- https://access.redhat.com/security/cve/CVE-2016-4020 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1313686 x_refsource_CONFIRMIssue TrackingThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html mailing-listx_refsource_MLISTMailing ListThird Party Advisory
- https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.html mailing-listx_refsource_MLISTPatchThird Party Advisory
- https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.html mailing-listx_refsource_MLISTPatchThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2016-4020
- https://security.gentoo.org/glsa/201609-01 vendor-advisoryx_refsource_GENTOOThird Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2016-4020
Change history (0)
No recorded changes yet.